New research suggests it is hard to promote the success of vaccination, but easy to scare mothers with the risks.

Infant immunisations are more likely to be delayed if women receive information during pregnancy that discourages infant immunisation, the study from the University of Auckland says, but when pregnant women receive encouraging information about immunisation it has no effect on the subsequent timeliness of infant immunisations.

Less than half of the pregnant women surveyed recalled receiving any information about infant immunisation during their pregnancy.

The study’s senior author Professor Cameron Grant says that for national immunisation programmes to yield their maximal health benefits, children must receive scheduled vaccinations on time. This is particularly important for the primary infant immunisation series where delay increases the risk of hospital admission due to vaccine-preventable disease.

“Pregnant women receive information that supports or opposes immunisation. This research set out to identify what proportion of pregnant women receive such information, the sources of that information and whether receipt of information about infant immunisation has any influence on the timing of their children’s immunisations,” he said.

Of those women who did not recall receiving any information during pregnancy, 70 per cent of their infants were immunised on time, compared with 57 per cent of infants of women who received discouraging information and 61 per cent of infants of women who received both encouraging and discouraging information.

The infants of women who received only encouraging information about infant immunisation during their pregnancy were no more likely to be immunised on time than the infants of women who received no information about infant immunisation during their pregnancy.

The main sources of immunisation information identified by the women were health care providers (identified by 35 per cent), family and friends (identified by 14 per cent), and media (identified by 14 per cent). Most said they received only encouraging information from health care providers, while the main sources of discouraging information were family and friends and media.

Professor Grant says he was concerned to see that one in six women who recalled receiving discouraging information identified health care providers as a source of that information.

“It is clear that pregnant women receiving information which discourages infant immunisation has a negative effect on subsequent health care delivery to that infant, even when they have also received information which encourages immunisation,” says Professor Grant.

“In contrast, the receipt of encouraging information about infant immunisation during the pregnancy is no more effective than receiving no information.

“The ambiguity created by pregnant women receiving conflicting advice about infant immunisation is an area which requires some focused attention.

“We cannot prevent pregnant women from being exposed to information discouraging immunisation, but we can improve the ways in which we deliver encouraging information and ensure that they meet the information needs of everyone.”